NHM-2A、BBTD和5RMS体系的激发态质子转移

发布时间：2018-05-23 20:54

本文选题：氢键 + 激发态质子转移　；参考：《辽宁大学》2017年硕士论文

【摘要】：在物理学、化学、生物学等研究中氢键是一种普遍存在的弱相互作用。很多微观结构和超分子结构都涉及氢键相互作用,像聚合物、溶质和溶剂复合物、蛋白质和DNA等。氢键相互作用可以在基态和激发态存在。激发态氢键相互作用被广泛研究,其在电子光谱移动、荧光猝灭、光诱导电子转移、内转换和分子内电荷转移等过程中扮演着重要的角色。质子转移是基于氢键作用的一种动力学过程而且具有广泛的应用,例如激光染料、LEDs、荧光传感器、分子开光、紫外线过滤器等。激发态质子转移研究备受关注。本文主要利用Gaussian 09软件研究了三种体系的质子转移机制,计算过程中选用的是密度泛函理论(DFT)和含时密度泛函理论(TDDFT)方法。包括9H-pyrido[3,4-b]indole(norharmane,NHM)与溶剂中的乙酸分子形成的三元复合物(NHM-2A)的链式质子转移过程,2,5-bis(benzoxazol-2-yl)thiophene-3,4-diol(BBTD)分子内质子转移的协同或逐步的机制,Methyl 5-R-Salicylates(5RMS)中不同取代基下的质子转移情况。从我们的研究中发现,NHM与两个乙酸分子形成的三元复合物的链式质子转移过程是一个逐步的转移过程。BBTD的荧光现象已经在实验上研究,实验中通过类比的方法确定了质子转移互变异构体的存在,但是却不能确定更详细的分子内的质子转移机制,通过势能面的计算,我们明确了BBTD分子内逐步的质子转移机制。通过研究Methyl 5-R-Salicylates在不同的R取代基下的质子转移情况,我们发现R取代基的电子释放能力越强,质子转移的势垒将越大,甚至不能发生质子转移。这说明理论的研究能更清楚地解释实验上不能明确的原理。
[Abstract]:Hydrogen bond is a common weak interaction in physics, chemistry, biology and so on. Many microstructures and supramolecular structures involve hydrogen bond interactions, such as polymers, solute and solvent complexes, proteins and DNA. Hydrogen bond interaction can exist in ground state and excited state. The excited hydrogen bond interaction has been widely studied and plays an important role in the electron spectral shift, fluorescence quenching, photoinduced electron transfer, internal conversion and intramolecular charge transfer. Proton transfer is a dynamic process based on hydrogen bonding and has a wide range of applications, such as laser dye LEDs, fluorescent sensors, molecular open light, ultraviolet filters and so on. The study of excited state proton transfer has attracted much attention. In this paper, the proton transfer mechanism of three systems is studied by using Gaussian 09 software. The density functional theory (DFT) and time-dependent density functional theory (TDDFT) are used in the calculation. The chain-type proton transfer process includes the synergistic or progressive mechanism of intramolecular proton transfer of benzoxazol-2-ylthiophene-34-diolen (BBTDs) in the presence of a ternary complex (NHM-2A) formed by 9H-pyrido [34-b] indoleurn norharmane (NHM) and acetic acid molecules in solvents (Methyl 5-R-Salicylates-5RMS). From our study, we found that the chain proton transfer process of the ternary complex of NHM and two acetic acid molecules is a gradual transfer process. The fluorescence phenomenon of BBTD has been studied experimentally. In the experiment, the existence of proton transfer tautomerism was determined by analogy, but the intramolecular proton transfer mechanism could not be determined in detail. Through the calculation of potential energy surface, we defined the gradual proton transfer mechanism in BBTD molecule. By studying the proton transfer of Methyl 5-R-Salicylates under different R-substituents, we find that the stronger the electron release ability of R-substituents is, the larger the proton transfer barrier will be, or even the proton transfer will not occur. This shows that the theoretical study can explain more clearly the principle that is not clear in the experiment.
【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.1

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